US3605588A - Photographic camera with electronically controlled lens diapharagm - Google Patents

Photographic camera with electronically controlled lens diapharagm Download PDF

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Publication number
US3605588A
US3605588A US779945A US3605588DA US3605588A US 3605588 A US3605588 A US 3605588A US 779945 A US779945 A US 779945A US 3605588D A US3605588D A US 3605588DA US 3605588 A US3605588 A US 3605588A
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US
United States
Prior art keywords
electromagnet
armature
current
capacitance
diaphragm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US779945A
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English (en)
Inventor
Wolfgang Ort
Clemens Hopfner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
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Eastman Kodak Co
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Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
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Publication of US3605588A publication Critical patent/US3605588A/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B7/00—Control of exposure by setting shutters, diaphragms or filters, separately or conjointly
    • G03B7/08—Control effected solely on the basis of the response, to the intensity of the light received by the camera, of a built-in light-sensitive device
    • G03B7/081—Analogue circuits
    • G03B7/085—Analogue circuits for control of aperture

Definitions

  • the present invention relates to a photographic camera 'with an electronically controlled lens diaphragm and a mechanically controlled shutter.
  • diaphragm control devices comprising holding magnet blocking means are known from a great number of embodiments.
  • the diaphragm usually is controlled by a photocell acting directly or through electronic amplifying and/ or switching circuitry in response to scene brightness.
  • Electromagnets are used as driving components, i.e., for producing mechanical forces.
  • An electromagnet places a considerable strain on the battery because of its high current consumption.
  • the resistance of the magnet coil winding is kept as low as possible. Considerably less force is necessary to hold the armature, however.
  • the electromagnet functions to attract its armature when the electronic system has reached a threshold value and to hold the armature until the shutter action is completed.
  • the battery whose capacity is limited by the restricted space in the camera body, is stressed to such an extent that its useful life is short. It is therefore necessary to replace the battery too often.
  • this problem is solved in a camera of the type described above which, when set for daylight operation, an electronic switching amplifier controlled by a photoresistor switches an electromagnet which operates a mechanical blocking device.
  • a threshold value When a threshold value is reached, the diaphragm motion is stopped at an optimal position as a function of the light conditions prevailing at the 3,605,588 Patented Sept. 20, 1971 moment the exposure is made.
  • the illuminated area of the photoresistor varies synchronously with and accord ing to the change in the lens diaphragm.
  • the problem of the high battery loading is solved by exciting the electromagnet with a capacitor connected in parallel with the collector circuit of the output transistor. The capacitor discharges through the output transistor when it goes into conduction so that the resulting current pulse acts on the electromagnet, which is connected in series with the emitter-collector path of the transistor.
  • This design permits the magnet coil winding to have a very low resistance without overloading the battery since the energy stored in the capacitor is used to move the armature. It is therefore possible to obtain high initial forces of approximately equal value upon each release action.
  • the capacitor can be selectively used for flash operation by a simple change in the circuit.
  • the sole figure shows a partially schematic, partially diagrammatic view of a preferred embodiment.
  • a member 3 which establishes both a diaphragm opening 5 and a photocell opening 6. Also shown is a member 4 which operates synchronously with member 3 to variably establish the diaphragm opening 5.
  • An armature-catch 13a is mounted for movement into engagement with teeth 3a to block further motion of the member 3. Armature 13a is actuated by an electromagnet 13 which is connected to the appropriate energizing circuitry described below.
  • the main switch 7 is closed, thereby connecting the electric circuitry to the battery 8.
  • the two-stage transistor circuit is brought into conducting position in a Way known in the art, i.e., the transistor 10 blocks while transistor 11 goes into conduction.
  • the capacitor 12 thus discharges through the emittercollector circuit of transistor 11 and through electromagnet 13. Consequently, the armature catch 13a of said electromagnet is attracted and moves to engage one of the teeth 3a of blade 3. Thus, the movement of the diaphragm is stopped.
  • Emitter resistor 14 serves three purposes. Besides being the emitter resistor for transistor 11, resistor 14 is a series resistor to provide the recharging of capactor 12 when the camera is in rest position, and it also determines the magnitude of the holding current, after the discharge current of the capacitor 12 has attracted the armature 13a.
  • armature 113a be self-locking
  • the geometric arrangement of the center of rotation 13b of the armature relative to the toothing 3a can be adjusted, and/or the form of the toothing itself can be adjusted.
  • Variable resistor 16 is connected in series with the battery and the photoresistor 9 to provide an input potential divider for the electronic switching amplifier; it is provided to adjust the threshold value at which the switch circuit is triggered whereby the electromagnet 13' is to attract armature 13a.
  • the aperture is defined, e.g., by distance setting. This is well known in the art and is therefore not shown. It is, however, important that in this case the electronic system is not needed and consequently disconnected from the current source 8 by an additional switch 17. The closing of switch 7 caused by the release member 1 is thus made ineffective.
  • the fiashlamp 18 is fired by closing the synchronized switch 19 causing the capacitor 12 to be discharged through the flashlamp.
  • a camera having an electromagnetic exposure control means connectable with a source of electric potential for selective energization of an electromagnet to move an armature from a rest position to an actuated position in response to a first magnitude of current flow through the electromagnet and to hold the armature in its actuated position in response to a second lesser magnitude of current flow through the electromagnet, the
  • switch means for selectively connecting said electromagnet in parallel with said capacitance, the magnitude of said capacitance, the resistance of the electromagnet and the potential of said source being proportioned so that discharge of said capacitance I through said electromagnet establishes a current of at least said first magnitude to flow through said electromagnet to thereby move said armature from its rest position to its actuated position;
  • an electromechanical exposure control energizable by a battery comprising:
  • photoresponsive means adapted to receive 1llumination from an object scene and having an electrical parameter which varies as a function of the level of scene illumination incident thereon;
  • an electromechanical transducer including an armature and an electromagnet energizable to move the armature from a rest position to an actuated position to adjust the position of the diaphragm member along its path to establish the size of the exposure aperture in response to a first magnitude of current flow through the electromagnet, and for holding the armature in its actuated position in response to a second lesser magnitude of current flow through the electromagnet;
  • electric circuit means operably coupled to said photoresponsive means and said electromagnet for controlling the energization of said electromagnet
  • said circuit means including a capacitance, switch means for selectively connecting said electromagnet in parallel with said capacitance to produce a current flow of at least said first magnitude from said capacitance through said electromagnet to move said armature to its actuated position
  • said circuit means being adapted to activate said switch means to connect said electromagnet in parallel with said capacitance when the level of scene illumination incident on said photoresponsive means reaches a predetermined level
  • resistance means connected in series with said capacitance to limit both the peak charging current of said capacitance and the holding current of said electromagnet, said resistance means having a resistance value that permits a current flow of at least said second magnitude from the battery through said electromagnet when said switch means is actuated.
  • an electromechanical exposure control energizable by a battery comprising:
  • photoresponsive means adapted to receive illumination from an object scene and having an electrical parameter which varies as a function of the level of scene illumination incident thereon;
  • an electromechanical transducer including an armature and an electromagnet energizable to move the armature from a rest position to an actuated position to adjust the position of the diaphragm member along its path to establish the size of the exposure aperture in response to a first magnitude of current flow through the electromagnet, and for holding the armature in its actuatedposition in response to a second lesser magnitude of current flow through the electromagnet;
  • electric circuit means operably coupled to said photoresponsive means and said electromagnet for controlling the energization of said electromagnet, said circuit means including a capacitance, first switch means for selectively connecting said electromagnet in parallel with said capacitance to produce a current of said first magnitude from said capacitance through said electromagnet to move said armature to its actuated position, said circuit means being adapted to activate said switch means to connect said electromagnet in parallel with said capacitance when the level of scene illumination incident on said photoresponsive means reaches a predetermined level, and resistance means connected in series with said capacitance to limit both the peak charging current of said capacitance and the holding current of said electromagnet, said resistance means having a resistance value that permits a current flow of at least said second magnitude from the battery through the electromagnet when said first switch means is activated; and

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure Control For Cameras (AREA)
  • Stroboscope Apparatuses (AREA)
US779945A 1968-06-25 1968-11-29 Photographic camera with electronically controlled lens diapharagm Expired - Lifetime US3605588A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1772718 1968-06-25

Publications (1)

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US3605588A true US3605588A (en) 1971-09-20

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US779945A Expired - Lifetime US3605588A (en) 1968-06-25 1968-11-29 Photographic camera with electronically controlled lens diapharagm

Country Status (3)

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US (1) US3605588A (enExample)
FR (1) FR2011619A1 (enExample)
GB (1) GB1268246A (enExample)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3750543A (en) * 1971-04-19 1973-08-07 Polaroid Corp Focus responsive exposure control system
US3777637A (en) * 1971-05-31 1973-12-11 Minolta Camera Kk Automatic exposure control device for a photographic camera
US3791278A (en) * 1971-07-19 1974-02-12 Polaroid Corp Photographic apparatus with solenoid powered instrumentalities

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5632128A (en) * 1979-08-22 1981-04-01 Olympus Optical Co Ltd Aperture control circuit of strobe synchronized camera

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3750543A (en) * 1971-04-19 1973-08-07 Polaroid Corp Focus responsive exposure control system
US3777637A (en) * 1971-05-31 1973-12-11 Minolta Camera Kk Automatic exposure control device for a photographic camera
US3791278A (en) * 1971-07-19 1974-02-12 Polaroid Corp Photographic apparatus with solenoid powered instrumentalities

Also Published As

Publication number Publication date
GB1268246A (en) 1972-03-22
FR2011619A1 (enExample) 1970-03-06

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